"Poland today is not a country that can show Europe the way, it's a country that has decided to go against European interests in many areas," Macron told a press conference in the coastal city of Varna in Bulgaria.
"Europe was built on public freedoms that Poland violates... It is placing itself on the margins of Europe's future history," said the centrist president who took office in May.
His remarks drew the ire of Polish Prime Minister Beata Szydlo.
"Perhaps (Macron's) arrogant comments result from lack of political experience, which I can understand, but I expect that he will make up for this shortcoming and will be more restrained in the future," she told the
right-wing wPolityce.pl news website on Friday.
The spat erupted on Macron's final day of a short tour through Austria, Romania and Bulgaria, as he seeks to win support for changing the so-called Posted Workers Directive at an EU summit on October 19th-20th.
The regulation lets firms send workers from low-wage countries to wealthier economies on short-term assignments without paying their hosts' social charges.
The rule has caused resentment in western countries like France, Germany and Austria, which argue it amounts to "social dumping" and creates unfair competition on national labour markets.
Backed by Berlin and Vienna, Paris wants the duration of the postings to be limited to 12 months - half the period proposed by the European Commission - and demands greater efforts to fight abuse of the directive.
The reform is a key election promise of 39-year-old Macron who has suffered plummeting approval ratings at home since his election.
But there has been staunch resistance in eastern and central Europe, where most of the cheap labour comes from.
Warsaw and Budapest say the proposals go too far and will undercut their interests.
Poland - the EU member that benefits most from the regulation - wants to keep its current rules intact.
An estimated 500,000 of Polish nationals are employed by Polish companies in other EU members.
"We will defend our position to the end, because it is a position that is in the interest of Polish workers," Szydlo said Thursday.
During his three-day diplomatic blitz, Macron met leaders from Austria, Slovakia, Romania, Bulgaria and the Czech Republic.
While Austrian Chancellor Christian Kern is an enthusiastic supporter of the proposals, the other heads of state reacted more cautiously.
"All the countries (in eastern Europe) know there's a problem and that things have to be changed," Bulgarian Prime Minister Boyko Borisov said Friday after talks with Macron.
But he warned against trying to push through the reform without the support of Budapest and Warsaw, echoing a sentiment also expressed by Slovakia.
"Poland and Hungary are our friends, and an important part of the EU. It would be harmful to see the relations between EU countries enter a phase of open confrontation," Borisov said.
Bucharest meanwhile insisted that any reform had to steer clear of undermining free market competition.
Macron said on Friday that he was finishing his regional visit with "the conviction that an agreement by majority vote is possible before the end of the year".
Brussels battle of wills
Next week, the French president will host leaders from Germany, Spain, Italy and the Netherlands for talks on the directive.
Franco-German unity is seen as a pre-requisite for an overhaul of the rule.
The issue is also part of a broader battle, with Brussels accusing Poland and Hungary of trying to cherry-pick parts of the EU membership while ignoring the bloc's fundamental principles.
The European Commission has launched legal procedures against both countries over controversial legislation and their refusal to accept migrants under a relocation programme.
Laurence Benhamou with Nina Lamparski in Vienna